The Federal Aviation Administration (FAA) has developed a datalink program for digital communication between aircraft and ground based computers. One of the potential uses of this digital datalink is in the dynamic control of such aircraft. The FAA is also conducting long range research programs with respect to automation aids that will require the air traffic controller to inform the ground-based computer of the tactical control actions that are to be taken by the aircraft so that the ground-based computer can generate more accurate information for use by the airborne computer.
Such digital data links between ground-based air traffic control computers and airborne flight deck computers could provide a number of potential advantages. These advantages include a reduction in both controller and pilot workload and a reduction in errors and misinterpretations that occur in voice communications between the controller and pilot. In general, such digital communication links can provide an exchange of data with greater speed and accuracy and with greater information content than is currently available with voice communication.
It will be appreciated that while digital data links possess the potential advantages discussed above, a number of possible problem areas must be addressed before the use of such a data communication link becomes practical. One of these potential problem areas concerns the nature of the interface through which the controller and the pilot are to communicate. Such an interface must maximize safety and accuracy, take into consideration the respective roles of man and machine, and keep the workload at an optimal level. It will be appreciated that due to the complexity of the air traffic control environment and the need to respond quickly to developing situations, issues involving the "human factor" in the communication interface are of paramount importance. In this latter regard, it is noted that while the pilot may select items from a menu on a computer screen or type in messages to be transmitted to the controller, these traditional data entry approaches may not always be appropriate for the controller.
Considering keyboard entry, using the standard "QWERTY" keyboard to enter all tactical maneuvering commands is an unrealistic burden to place on the controller because: (i) many controllers simply cannot type fast enough to input commands using the keyboard; (ii) keyboard input requires the controller to take his attention away from the screen and switch from a spatial model of the airspace to a verbal/textual model of command; and (iii) the error rate for keyboard entry is unacceptably high. In the latter regard, it is believed that the addressing errors produced from transpositions or misstruck keys would probably be even higher than the same types of errors that occur today using conventional voice communication.
Regarding the use of menus, this is a possible alternative (or companion) approach to message creation. With this approach, the controller would construct a message from predefined menus corresponding to a predetermined grammar for the air traffic control commands. Although this use of menus would reduce keystroke errors, this approach still requires a shift from a spatial mental picture to a verbal/textural mental process. Further, the selection of phrases from a series of menus is likely to be too time consuming to allow the construction of messages in emergencies or in other time critical situations.
As discussed in detail below, the present invention provides a controller with a spatial representation of the airspace being controlled. It will be understood that such a spatial representation is not unique and is employed in situation displays now being used. Further, modern user interfaces (such as the Macintosh or MS Windows interface) provide for direct screen manipulation by permitting a user to select items on a screen using a mouse and a cursor. In air traffic control systems a rudimentary form of this capability is available in that, for example, controllers can use a "trackball" (a hand operated pointing device) to select an aircraft for "handoff".